Conventionally, a washer fluid heating device has been mounted on a vehicle, etc. to remove frost in winter. For example, Patent Literature 1 describes a washer fluid heating device having a structure in which a heating chamber is accommodated in a heat-retaining hot water storage chamber and an electric heater is accommodated inside the heating chamber. In this heating device, a washer fluid in the heat-retaining hot water storage chamber may be allowed to flow into the heating chamber by opening an outflow passage for the washer fluid at an upper part of the heating chamber. After the washer fluid is heated by the electric heater inside the heating chamber, the washer fluid is supplied to a washer nozzle by driving of a washer pump and sprayed from the washer nozzle. In addition, Patent Literature 2 describes a vehicular washer device including a heating and heat insulating device that heats a washer fluid and keeps the washer fluid warm. This device is provided with an outlet that allows the washer fluid to flow out and a gas phase removal pipe for discharging gas.